Air brake



Patented Aug. 9, 1932 UNITED STATES 1 ATrs.NTy OFFICE JAMES D. CAETIN,OF WATERTOWN, NEW YORK, ASSIGNOR TO THE NEW YORK AIR BRAKE COMPANY, ACORPORATION F NEW JERSEY .am BRAKE Application led October 9, 1930.Serial No. 487,613.

This inventionrelates to air brakes, and particularly to apparatus knownin the air brake art as ET equipment.

The ET equipment is used on locomotives to apply and release the engineand tender brakes, the air for applying the brakes being drawn directlyfrom the main reservoir. The most important element of the ET equipmentis the so-called distributing valve which consists of two portions, anequalizing portion which is in effect a triple valve responsive topressure changes in the brake pipe, and the application portion which isin e'ect a pressure regulating valve having an application piston(so-called) subject on one side to pressures established by theequalizing portion just mentioned, and subject on the opposite `side tobrake cylinder pressure. The application piston operates two valves;one, the application valve which controls How from the main reservoir tothe brake cylinder to apply the brakes, and the other, the exhaustvalve, which controls flow from the brake cylinder Ito atmosphere torelease the brakes.

The application piston and the application and exhaust valves functionto establish and maintain in the brake cylinder a pressure correspondingto the pressure established against Y the application piston by theequalizing portion. The application valve is customarily of the slidetype and is held to its seat by main reservoir pressure. Consequently itmust be housed in a chamberoutside of the chamber in which brakecylinderpressure exists. This fact requires that the application valvebe offset relatively to the stem of the piston.

Structures of this general character are illustrated'in a number ofpatents; for'example, the following three patents to Walter V. Turner:-1,109,175, in which the piston is numbered 8 and the olfsetapplication valve 11; 1,129,318, in which the pis-ton is numbered 78 andthe application valve is the slide valve in the chamber numbered81;1,130,448, in

which the piston is numbered'23 and the application valve is numbered21. Y

A commercial embodiment of the ET distributing valve is fullyillustrated and described in Instruction Pamphlet No. 5032, issuedDecember 1927, byThe New York Air Brake Company, and entitled No. 6 ETLocomotive Brake'Equipment. Fig. 19 on'page of that pamphlet illustratesthe commercial structure upon which the present inven- *Y tion is animprovement.

The purpose of the present -invention is to improve the offset drivingconnection between the application piston and the application valve. Thepiston and its stem are guided for right line reciprocating movement.The intent is to have the valve seat for the sliding application valveabsolutely-parallel with this line of motion. Because of minor errors inmachining and more commonly bev piston stem, to the end that thevalve'may aci commodate itself to any slight irregularitie in thealignment of the seat.

The invention willnow be described with reference to the accompanyingdrawing, in which Y Fig. 1 is a fragmentary view of` adistributingvalve; in this view the aplication valve mechanism is shown complete andthe equaliziig portion or triple valve portion is omitte v Fig. 2 is asection on the line 2 2 of Fig. 1.

Fig. 3 is a fragmentary view of a portion of Fig. 1 on a slightlyenlarged scale.

Figs. 4, 5 and 6 are, respectively, face, side and end elevations of thedriving pin.

'In the drawing, 11 represents the body casting of'a distributing valvewhich has at one end an enlargement having a cylinder bushing 12. Inthis bushing slides a piston 13 gested, the equalizing portion is ineifect a triple valve and functions, in response to changes in brakepipe pressure, to establish in the chamber 19 pressures which correspondto the brake cylinder pressures throughout the tra-inL The. space- 225to,` the right of: the piston 13 is subject to brake cylinder pressure,as is the space within the valve-chamber bushing 23. 24 is air exhaustpassage which communicates` with exhaust ports 25? in the' bushing` 23'.These ports are controlled by a slide valve 26 which is held to its seatby a bow spring 27 reacting against the, stem. 14. `The valve 26 haslost motion relatively to the stem 1'5, such motion` being limited bythe shoulders 28a-rides); y Y

Thefright end ot thefstem 14 is guided for right linefmotion in; thebushing 23. by a` spider having lugs 31. Theselugs, as illustrats ed,are behind-ithe-planeofisectiomand, therefore,.do not appear to contactthe bushing 23, but asa matter of fact, they and simi-lar lugs forward.of the plane of section do enter into sliding engagement with thebushing and function, to maintain the alignment of the stem- 14 and;confine, the` stem tovv strict longi-k tudinalfreciprocation. The partsAare shown inl release position, that is, with the.4 piston 13 tothe leftat its` limit of motion against the cylinder'head32.. l y

rIhe right end ofthe stem 14` is hollow to receive a.Y spring 33vr andaV yielding.A stop 34, retained by a; cap nut 35. rlhe spring andyielding stop. function to`V assist in` the shiftingof thepiston 13 androdi 14 toflap position after an application.

Mounted on the upper portion'A of. the distributing valve body7 11- isthe application valve housing 36 which is connected to theY mainAreservoir so that the space 37' within houm'ngl is subject to. main.reservoir pressure.. The housing 36 is heldin placeby screws38 as.-shown. l

Formed on the upper portion of the body 11 within the housing 361s theapplication valve seat 39 is provided withan el'ongated slot 41v inwhich` reciprocates the d'riv-` ingpin represented? generally by thenumeral 42. 'his` pinmakes a tightslip` fit with al the stem 14. Correctassembly' is insured by a. longitudinal slot 43 formed in the driving:pin 42V andreceiving a guidepint 44 mounted inthe stem 14. It will beob-V servedn fromlig. ithat thedriving pin 42 is of generallycylindrical contour,l with two: opposed. flat sid'es45and` 46, one ofwhich theY groove 43 is formed. Y Y

The1 upper end, of the driving; pin 42.1enters` a cylindrical opening 47in. theapplication slide valve 48... Thisslide: valvegworks'on the seat39 and is provided with anv admission*- port 49 throughl which mainreservoir airV lowsto 1the brake-cylinder chamber 22`byway of slot 41(which, alsofservesf as a seaty port),

trated, for example, in the Turner patents mentioned?, andinthellnstruction Pamphlet above identified. Unless -a very loose andunsatisfactory fit was used, no opportunity Y"was'alforded for the valve48 to accommo- -date itselfto misa-lignment of the seat 39.

` The present'invention is designed to overcome, this diificulty.Thevalve 48v isl formed witlr a; relief recessV 52m its lower Aface asheretofore. The drivingpin42 is'so-formed that it engages the-valve48'only over a very limited lengthpof; the driving pin. The areaoffengagement consists; of a peripheral Zone 53Ywhi'ch; is .immediatelyabove the relief recess 52'., B'olthf above and'below the Zone 53 thedrivingipin is taperedz slightly as indi#l catedi at 54 `and 55.1 .Thedimension ofthe zone 53 measured in the direction of the length `of thepin 42 is of the order of oneeighth of an;v inch in valves ofpresentcom.- mercial size. VThe taper lof the portions 54 and. 55 isvery slight and is ofthe order of one degree Yandgfortysfourf minutes.

'lhev value of the taper is arrived at as follows-z Knowingthe' maximumallowable clearance. between` the Zone 53 on the pin and the` wallsof'therecess 47, itis possibleto determinethe maximumA amount thatn thevalve 48. may` cant relatively to the piny 42. The angleof taper is sochosen that at this maxi'- mum angle: ofi cant, the taper 54 willcontact with. the valve, 38` throughout the entire length-.ofthe taper;yThe idea is to secure the maximum contact area in the least favorablepositionl in; the valve 48that is, in the position4 in which it is mostcanted.

Itis desirablethat the zone 53 on the pin be as close, as` possible tothe planeofl slid'- mgf contact between the valve 48 andv the valve seat39'. Eor'manufacturing reasons it is' desirable` to have the' reliefrecess '52, but this-ismade as-shallow as is reasonably practicable.-

' It follows from: the-construction just outlined that the valve A'42is'` driven adjacentits plane" of resistance and is free to tilt to ac'-Vcommo'date-itselfto misalignment of the valve seat.

Topreclude erroneous-assembly of the parts thereV is a'rguide pin 56 inVrecess 47 (see Fig. 2)' which, like the'p-in 44, enters vthegslot 43.

The hole 57 which is formed at the upper end' of the pin 42 voffersmeans forengaging the pin 421 tof withdraw itfrom the hole in thestemlliA It' mustbe withdrawn to dismount the'- device.

Whilel prefer: the-straightv taper portions 54 and 55 above described,and while I prefer to locate the Zone of contact 53 as near the face ofthe valve seat 39 as is practically possible, it is apparent thatapproximately equivalent results might be secured by other arrangements.Hence, no limitation to the exact construction is implied by thedetailed description given.

I claim l The combination of a rod; means for guiding the same inlongitudinal reciprocations; a valve seat substantially parallel withthe path of such reciprocation and having a longitudinal slot; a slidevalve slidable on said seat, and having in its face a recess whichoverlies said slot; and a driving connection between said rod and valvecomprising a pin rigidly mounted in said rod, and extending laterallythrough said slot and into the recess in said valve, said pin having anarrow bearing portion tting said recess with a working Y clearance, andat least onetapered portion adjacent said bearing area, the taperapproximating the angle of valve tilt permitted by the maximum allowableworking clearance.

2. The combination of claim 1, further characterized in that the recessin the valve is of circular cross section, and that the pin, includingthe bearing area and taper is of circular cross section with its sidescut away.

In testimony whereof I have signed my name to this specification.

TAMS D. CARTIN.

